Water jet propeller

ABSTRACT

To simplify a mounting job for a filter and a lid at a water intake port. A filter accommodation chamber of a cylindrical shape forms a water intake port that is provided in a side wall of a stator having therein an impeller rotatably disposed. A filter of a cylindrical shape is placed in the filter accommodation chamber and an opening in the filter accommodation chamber is closed by a lid of a circular shape through either screwing or press-fitting. A flow path is integrally formed with a peripheral wall of the filter accommodation chamber. A bottom portion of the cylindrical filter is formed into an inclined surface. An inclined step portion, which abuts against an edge portion of the inclined surface of filter, is formed in the filter accommodation chamber. In addition, an opening, which communicates with the flow path when the inclined surface edge portion of the cylindrical filter and the inclined step portion abut against each other so that the two are brought into coincidence with each other, is formed in the cylindrical filter. Part of an inner peripheral surface of the filter accommodation chamber and part of an outer peripheral surface of the cylindrical filter may be formed into a flat surface.

BACKGROUND OF THE INVENTION CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority under 35 USC 119 toJapanese Patent Application No. 2001-284064 filed on Sep. 18, 2001 theentire contents thereof is hereby incorporated by reference.

[0002] 1. Field of the Invention

[0003] The present invention relates to a water jet propeller used inships and, more particularly, to a structure of a water intake portthereof.

[0004] 2. Description of Background Art

[0005] Japanese Patent Laid-open No. Hei 10-119883 discloses aconventional water jet propeller.

[0006] FIGS. 6(a) to 6(c) illustrate the water jet propeller, with FIG.6(a) being a cross-sectional view, FIG. 6(b) being an enlargedcross-sectional view taken along line b-b in FIG. 6(a), and FIG. 6(c)being a cross-sectional view taken along line c-c in FIG. 6(a).

[0007] The water jet propeller is mounted to a rear portion of a shipbody 1. There is provided a water intake port 5 provided with a filter 4in a side wall of a stator 3, in which an impeller 2 is rotatablydisposed.

[0008] The impeller 2 is coupled to a drive shaft 6, a front portion ofwhich is coupled to an output shaft of an engine not shown. When theimpeller 2 is rotatably driven by the engine and spurts of a stream ofwater are sent through a nozzle 3 a of the stator 3 to propel the shipbody 1.

[0009] As shown in FIG. 6(b), the water intake port 5 is opened in asubstantially rectangular shape. A substantially rectangular filter 4 isthen mounted in this opening which, in turn, is covered with a lidmember 7 which also is of a substantially rectangular shape.

[0010] The lid member 7 is provided integrally with a pipe section 7 athat communicates with the water intake port 5. A flexible hose 9 isconnected by way of a connection pipe 8 to the pipe section 7 a. An endportion not shown of the flexible hose 9 is, in turn, connected to theengine.

[0011] When the impeller 2 is rotatably driven, therefore, part of awater stream on a downstream side thereof is supplied from the waterintake port 5 to the engine by way of the filter 4 and further throughthe pipe section 7 a of the lid member 7, the connection pipe 8, and theflexible hose 9, thus being used as engine coolant.

[0012] Referring to FIGS. 6(b) and 6(c), the filter 4 is provided with aflange 4 b, while the lid member 7 is also provided with a flange 7 b.The filter 4 and the lid member 7 are jointly fastened together usingfour bolts 7 c with the flanges 4 b, 7 b mated to each other. Thus, thefilter 4 and the lid member 7 are removably mounted with respect to theside portion of the stator 3.

[0013] According to the conventional water jet propeller described inthe foregoing paragraphs, the filter 4 and the lid member 7 of the waterintake port 5 are shaped into a substantially rectangle, and they aremounted to the stator 3 by jointly fastening them together using fourbolts 7 c with the flanges 4 b, 7 b mated to each other. This makes themounting job extremely laborious.

SUMMARY AND OBJECTS OF THE INVENTION

[0014] It is therefore an object of the present invention to solve thisproblem and to provide a water jet propeller that allows a filter and alid to be mounted with ease.

[0015] To achieve the foregoing object, according to the presentinvention, there is provided a water jet propeller wherein a waterintake port includes a filter that is provided in a side wall of astator containing a rotatable impeller, wherein the side wall of thestator is provided with a tubular filter accommodation chamber thatforms the water intake port. A tubular filter is housed in the filteraccommodation chamber and an opening is formed in a circular shape inthe filter accommodation chamber and is closed by a circular lid throughtightening screws or press-fitting.

[0016] According to the present invention, a flow path is integrallyformed with respect to a peripheral wall of the filter accommodationchamber and a bottom portion of the tubular filter is formed by aninclined surface that is inclined with respect to an axial direction ofthe tubular filter. In addition, an inclined step portion is formed inthe filter accommodation chamber so as to abut against and receive anedge portion of the inclined surface of the tubular filter. An opening,which communicates with the flow path when the inclined surface edgeportion abuts against the inclined step portion so that the two portionsare brought into coincidence with each other, is formed in the tubularfilter.

[0017] According to the present invention, a flow path is integrallyformed with respect to a peripheral wall of the filter accommodationchamber. An inner peripheral surface of the filter accommodation chamberand an outer peripheral surface of the tubular filter are partiallyformed into a flat surface. An opening, which communicates with the flowpath when the flat surface portion of the tubular filter coincides withthe flat surface portion of the filter accommodation chamber, is formedin the tubular filter.

[0018] In the water jet propeller according to the present invention,the water intake port that includes the filter is provided in the sidewall of the stator containing the rotatable impeller. The tubular filteraccommodation chamber forming the water intake port is provided in theside wall of the stator. The tubular filter is housed in the filteraccommodation chamber with the circular opening formed in the filteraccommodation chamber. The circular lid is either screwed orpress-fitted in position to close the circular opening. According to thewater jet propeller having this arrangement, the filter and the lid canbe mounted to the side wall of the stator by simply closing the openingin the filter accommodation chamber through either screwing orpress-fitting, after the tubular filter has been placed in the tubularfilter accommodation chamber.

[0019] Namely, in the water jet propeller according to the presentinvention, it is remarkably easier to mount the filter and the lid thanin the conventional arrangement.

[0020] According to the water jet propeller of the present invention,the flow path is integrally formed with respect to the peripheral wallof the filter accommodation chamber and the bottom portion of thetubular filter is formed by the inclined surface that is inclined withrespect to the axial direction of the tubular filter, the inclined stepportion is formed in the filter accommodation chamber so as to abutagainst and receive the edge portion of the inclined surface of thetubular filter. The opening, which communicates with the flow path whenthe inclined surface edge portion abuts against the inclined stepportion so that the two portions are brought into coincidence with eachother, is formed in the tubular filter. All this offers the followingfunction.

[0021] Namely, in the conventional water jet propeller describedearlier, the flow path from the filter accommodation chamber is formedby the pipe section 7 a that is integrated with the lid member 7.Therefore, if the lid member 7 is mounted in a reverse direction withrespect to a fore-and-aft direction, the flow path 7 a is also mountedin a reverse direction with respect to the fore-and-aft direction. Moreattention should therefore be paid to the mounting of the lid member 7,thus making the mounting job even more laborious.

[0022] According to the water jet propeller of the present invention, onthe other hand, the problems inherent in the conventional technologywill not occur, since the flow path is formed integrally with respect tothe peripheral wall of the filter accommodation chamber.

[0023] In addition, the bottom portion of the tubular filter is formedby the inclined surface that is inclined with respect to the axialdirection of the tubular filter, the inclined step portion is formed inthe filter accommodation chamber so as to abut against and receive theedge portion of the inclined surface of the tubular filter. In view ofthe opening, which communicates with the flow path when the inclinedsurface edge portion abuts against the inclined step portion so that thetwo portions are brought into coincidence with each other, formed in thetubular filter, the flow path in the filter accommodation chamber andthe opening in the filter are automatically brought into communicationwith each other when the tubular filter is inserted in the filteraccommodation chamber and the edge portion of the inclined surface ofthe tubular filter abuts against (or fit into) the inclined step portionof the filter accommodation chamber.

[0024] This helps make the mounting job of the filter and the lid eveneasier.

[0025] According to the water jet propeller of the present invention,the flow path is integrally formed with respect to the peripheral wallof the filter accommodation chamber. The inner peripheral surface of thefilter accommodation chamber and the outer peripheral surface of thetubular filter are partially formed into the flat surface and theopening, which communicates with the flow path when the flat surfaceportion of the tubular filter coincides with the flat surface portion ofthe filter accommodation chamber, is formed in the tubular filter. Thisoffers the following additional function.

[0026] Namely, as described earlier, in the conventional water jetpropeller, the flow path from the filter accommodation chamber is formedby the pipe section 7 a that is integrated with the lid member 7 and,therefore, if the lid member 7 is mounted in a reverse direction withrespect to the fore-and-aft direction, the flow path 7 a is also mountedin a reverse direction with respect to the fore-and-aft direction. Moreattention should therefore be paid to the mounting of the lid member 7,thus making the mounting job even more laborious.

[0027] According to the present invention, on the other hand, theproblems inherent in the conventional technology will not occur, sincethe flow path is formed integrally with respect to the peripheral wallof the filter accommodation chamber.

[0028] Since the inner peripheral surface of the filter accommodationchamber and the outer peripheral surface of the tubular filter arepartially formed into the flat surface, and the opening, whichcommunicates with the flow path when the flat surface portion of thetubular filter coincides with the flat surface portion of the filteraccommodation chamber, is formed in the tubular filter, the flow path inthe filter accommodation chamber and the opening in the filter areautomatically brought into communication with each other when thetubular filter is inserted in the filter accommodation chamber so thatboth of the above-mentioned flat surface portions coincide with eachother.

[0029] Therefore, the job of mounting the filter and the lid becomeseven easier.

[0030] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

[0032]FIG. 1 is a partly cutaway schematic side elevational view showinga typical small planing boat employing one embodiment of a water jetpropeller according to the present invention;

[0033]FIG. 2 is a schematic plan view showing the same;

[0034] FIGS. 3(a)-3(b) illustrate the jet pump 30, FIG. 3(a) being afragmentary side sectional view and FIG. 3(b) being a cross-sectionalview taken along line b-b in FIG. 3(a);

[0035] FIGS. 4(a)-4(d) illustrate a stator 31 of the jet pump 30, FIG.4(a) being a front elevational view (looking the ship body from thefront), FIG. 4(b) being a side elevational view, FIG. 4(c) being a planview of FIG. 4(b), and FIG. 4(d) being a cross-sectional view takenalong line d-d in FIG. 4(c);

[0036] FIGS. 5(a)-5(d) illustrate a filter, FIG. 5(a) being a sideelevational view (as viewed from the side of the ship body from a side),FIG. 5(b) being a plan view of FIG. 5(a), FIG. 5(c) being a sideelevational view of FIG. 5(a), and FIG. 5(d) being a cross-sectionalview taken along d-d in FIG. 5(a); and

[0037] FIGS. 6(a), 6(b) and 6(c) are explanatory drawings of theconventional technology.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The embodiments of the present invention will be described withreference to the accompanying drawings.

[0039]FIG. 1 is a partly cutaway schematic side elevational view showinga typical small planing boat employing one embodiment of a water jetpropeller according to the present invention. FIG. 2 is a schematic planview showing the same.

[0040] As shown in FIGS. 1 and 2, a small planing boat 10 is a ridingtype small watercraft, in which a passenger sits on a seat 12 on a shipbody 11 and grips a handlebar 13 provided with a throttle lever to steerthe boat.

[0041] The ship body 11 is of a floating body structure that forms aspace 16 internally between a hull 14 and a deck 15 joined to eachother. An engine 20 is installed on the hull 14 inside the space 16. Inaddition, a water jet propeller (hereinafter referred to also as a jetpump) 30 is provided as a propulsion means driven by the engine 20 thatis installed in a rear portion of the hull 14.

[0042] The jet pump 30 is provided with an impeller 32 disposed inside aflow path 18 that extends from a water inlet port 17 opened in a bottomof the boat to a jet port 31 c 2 opened in a trailing edge of the shipbody. A deflector 38 is provided adjacent to the jet port 31 c 2. Ashaft (drive shaft) 22 for driving the impeller 32 is coupled to anoutput shaft 21 of the engine 20 by way of a coupler 23. When theimpeller 32 is rotatably driven by the engine 20 through the coupler 23and the shaft 22 spurts of water taken in through the water inlet port17 are sent from the jet port 31 c 2 through the deflector 38, thuspropelling the ship body 11. A driving speed of the engine 20, or apropulsion force provided by the jet pump 30, is controlled bycircularly moving a throttle lever 13 a (see FIG. 2) of the handlebar 13either forward or backward. The deflector 38 is connected to thehandlebar 13 through a control cable not shown. It is operated as thehandlebar 13 is turned either forward or backward as necessary to changea direction of travel of the ship body 11.

[0043] Referring to FIG. 3(a) and 3(b), the jet pump 30 is provided witha stator (duct) 31 that forms the flow path 18 communicating with thewater inlet port 17 (see FIG. 1) provided in the bottom portion of theship body 11, with the impeller 32 disposed inside the stator 31. Abearing portion 33 of the impeller is provided inside the stator 31. Acap 34 plugs up a trailing edge of the bearing portion 33.

[0044] The jet pump 30 is mounted removably to the hull 14 when a flangeportion 31d (see FIGS. 4(a)-4(d)) formed at a front portion of thestator 31 is secured to the hull 14 using bolts not shown.

[0045] The stator 31 is provided with an impeller accommodation portion31 a, inside which the impeller 32 is disposed, a bearing accommodationportion 31 b, and a nozzle portion 31 c (see FIG. 1). The impelleraccommodation portion 31 a and the bearing accommodation portion 31 bare formed integrally with each other. The bearing portion 33 is formedintegrally within the bearing accommodation portion 31 b through astator blade 31 b 1.

[0046] A front portion of a boss portion 32 a of the impeller 32 isengaged with splines 22 b formed on a rear end of the drive shaft 22 andthe impeller 32 turns with the drive shaft 22. As noted earlier, theleading edge of the drive shaft 22 is coupled to the output shaft 21 ofthe engine 20 mounted in the ship body 11 through the coupler 23 (FIG.1).

[0047] An impeller shaft 35, which supports a rear portion 32 b of theboss portion 32 a of the impeller 32, is rotatably supported on thebearing portion 33 through ball bearings 33 a, 33 b. External threads 35a are formed on a leading edge of the impeller shaft 35. The externalthreads 35 a engage internal threads formed on the rear portion 32 b ofthe boss portion of the impeller 32, which provides a connection betweenthe impeller 32 and the impeller shaft 35.

[0048] In summary, the front portion of the boss portion 32 a of theimpeller 32 is coupled to the shaft 22, while the rear portion 32 b ofthe boss portion is coupled to the impeller shaft 35, which allows theimpeller 32 to turn with the shaft 22 and the impeller shaft 35.

[0049] There are formed, at a front portion of the cap 34, an insertionportion (a cylindrical portion) 34 b to be inserted into a rear portionof the bearing portion 33 and three (only one is shown) insertion holes34 c for a screw 36 (see FIG. 3(a)). A groove, into which an O-ring 34 eis mounted, is formed at the cylindrical insertion portion 34 b.

[0050] The cap 34 is therefore mounted to the rear portion of thebearing portion 33 as follows. Namely, the insertion portion 34 b isinserted (press-fitted) into the rear portion of the bearing portion 33with the O-ring 34 e mounted to the insertion portion 34 b as shown inFIG. 3(a) and the screw 36 is finally tightened.

[0051] A partial cutout 34 d is formed on an abutting surface betweenthe cap 34 and the bearing portion 33. During maintenance serviceprocedures, the cap 34 can be easily removed by inserting a tip of atool (for example, a screwdriver) into this cutout 34 d with the screw36 removed.

[0052] Referring to FIGS. 3 and 4, a filter accommodation chamber 31 gof a tubular shape (a cylindrical shape according to the embodiment) isformed integrally on a side wall 31 e of the stator 31, serving to forma water intake port 31 f in a portion downstream of the impeller 32. Afilter 40 of a tubular shape (a cylindrical shape according to theembodiment) is housed in the filter accommodation chamber 31 g as shownin FIG. 3(b). An opening 31 h in the filter accommodation chamber 31 gis closed by a circular lid 50 that is screwed into position. Theopening 31 h may instead be closed by press-fitting the lid 50.

[0053] Referring to FIGS. 4(a)-4(d), a flow path 31 j, through whichwater from the water intake port 31 f flows in, is integrally formed ina peripheral wall 31 i of the filter accommodation chamber 31 g. Acoolant hose is connected to an end portion 31 k of the flow path 31 jby way of a joint pipe not shown, through which coolant is supplied tothe engine 20.

[0054] Referring to FIGS. 5(a)-5(d), the filter 40 is provided with acylindrical portion 41 and a bottom portion 42 formed integrallytherewith. A number of holes 43 are made in the bottom portion 42. Thediameter of each of the holes 43 should be about 3 mm.

[0055] In addition, there is formed an opening 44 of a U-shaped cutoutin the cylindrical portion 41.

[0056] Referring to FIG. 4(b), part of an inner peripheral surface ofthe filter accommodation chamber 31 g is formed into a flat surface (theflat surface portion is indicated by a reference numeral 31 m).Referring further to FIGS. 5(a) and 5(c), part of an outer peripheralsurface of the tubular filter 40 is also shaped into a flat surface (theflat surface portion is indicated by a reference numeral 45).

[0057] When the filter 40 is inserted into the filter accommodationchamber 31 g , therefore, unless these flat surface portions 31 m and 45are properly aligned with each other, the filter 40 cannot be inserted.When the filter 40 is inserted into the filter accommodation chamber 31g with the flat surface portions 31 m and 45 aligned, the opening 44 inthe filter 40 opposes the flow path 31 j in the filter accommodationchamber 31 g brings the two into communication with each other [see FIG.3(b)].

[0058] Furthermore, according to the embodiment, the bottom portion 42of the tubular filter 40 is formed by an inclined surface 46 that isinclined with respect to an axial direction [a right-and-left directionin FIGS. 5(c) and 5(d)] of the tubular filter 40, as shown in FIGS.5(a)-5(d). As shown further in FIG. 3(b) and FIG. 4(d), an inclined stepportion 31 n, which abuts against and receives an edge portion 47 of theinclined surface 46 of the tubular filter 40, is formed in the filteraccommodation chamber 31 g.

[0059] When the filter 40 is inserted into the filter accommodationchamber 31 g, therefore, the inclined surface 46 at the bottom portion42 of the filter must be brought into coincidence with the inclined stepportion 31 n of the filter accommodation chamber 31 g, otherwise, a headportion 48 of the filter 40 protrudes from the filter accommodationchamber 31 g, thus preventing the filter 40 from being completely housedin the filter accommodation chamber 31 g, which hampers the lid 50 frombeing mounted in position. If the inclined surface 46 of the filterbottom portion 42 is brought into coincidence with the inclined stepportion 31 n of the filter accommodation chamber 31 g as the filter isinserted into the filter accommodation chamber 31 g, the opening 44 inthe filter 40 opposes the flow path 31 j in the filter accommodationchamber 31 g, bringing the two into communication with each other [seeFIG. 3 (b)].

[0060] According to this embodiment, the following two arrangements areemployed; namely:

[0061] an arrangement, in which partial flat surface portions 31 m and45 are formed on the inner peripheral surface of the filteraccommodation chamber 31 g and the outer peripheral surface of thefilter 40; and,

[0062] ii. an arrangement, in which the bottom portion 42 of the tubularfilter 40 is made into the inclined surface 46 and the inclined stepportion 31 n is formed in the filter accommodation chamber 31 g.

[0063] It is nonetheless possible to employ either one of these twoarrangements i and ii.

[0064] Referring to FIGS. 3(a)-3(b), a hexagon recessed portion 51 isformed in the lid 50 at a head portion thereof and, in addition,external threads 52 are formed on an outer periphery thereof. Internalthreads 31 p are formed, on the other hand, on an inner peripheralsurface on an upper portion of the filter accommodation chamber 31 g.

[0065] The opening 31 h in the filter accommodation chamber 31 g can beeasily plugged with the lid 50 by a manner that when, after the filter40 has been housed in the filter accommodation chamber 31 g as describedabove, the two types of threads 52, 31 p are brought into threadedengagement with each other by a tool engaged in the hexagon recessedportion 51 in the lid.

[0066] According to the embodiment, referring to FIG. 3(a) and FIG.4(b), there is provided a partial recessed portion 31 q on an innerperipheral surface in the opening 31 h of the filter accommodationchamber 31 g. After the lid 50 has been mounted in the opening 31 h ofthe filter accommodation chamber 31 g, a tool is inserted into therecessed portion 31 q for collapsing the threads 52 in the lid 50,thereby preventing the lid 50 from thereafter turning and thuspreventing the lid 50 from coming off the filter accommodation chamber31 g.

[0067] According to the water jet propeller having arrangements asdescribed above, the following operational effects can be achieved.

[0068] The tubular filter accommodation chamber 31 g that forms thewater intake port 31 f is provided on the side wall 31 e of the stator31, inside which the impeller 32 is rotatably disposed. The tubularfilter 40 is housed in the filter accommodation chamber 31 g. Theopening 31 h is formed circularly in the filter accommodation chamber 31g and is closed by the circular lid 50 through screwing orpress-fitting. Thanks to this arrangement, the filter 40 and the lid 50can be mounted to the side wall 31 e of the stator 31 by placing thetubular filter 40 in the tubular filter accommodation chamber 31 g andclosing the opening 31 h in the filter accommodation chamber 31 g withthe circular lid 50 through screwing or press-fitting.

[0069] Namely, according to this water jet propeller, the mounting jobof the filter 40 and the lid 50 is made remarkably simpler as comparedwith the conventional type.

[0070] (b) The flow path 31 j is integrally formed with respect to theperipheral wall of the filter accommodation chamber 31 g. The bottomportion of the tubular filter 40 is formed by the inclined surface 46that is inclined with respect to the axial direction of the tubularfilter. The inclined step portion 31 n, which abuts against and receivesthe edge portion 47 of the inclined surface 46 of the tubular filter 40,is formed in the filter accommodation chamber 31 g. In addition, theopening 44, formed in the tubular filter 40, communicates with the flowpath 31 j when the inclined surface edge portion 47 and the inclinedstep portion 31 n abut against each other so as to bring the two intocoincidence with each other. These arrangements offer the followingadditional operational effects.

[0071] Namely, in the conventional water jet propeller describedearlier, the flow path from the filter accommodation chamber is formedby the pipe section 7 a formed integrally with the lid member 7. As aresult, if the lid member 7 is mounted in a reverse direction withrespect to a fore-and-aft direction, the flow path 7 a is also mountedin a reverse direction with respect to the fore-and-aft direction. Moreattention should therefore be paid to the mounting of the lid member 7,thus making the mounting job even more laborious.

[0072] According to the water jet propeller according to the embodimentof the present invention, on the other hand, such a problem inherent inthe conventional technology will not occur, since the flow path 31 j isformed integrally with respect to the peripheral wall of the filteraccommodation chamber 31 g.

[0073] Furthermore, the bottom portion of the tubular filter 40 isformed by the inclined surface 46 that is inclined with respect to theaxial direction of the tubular filter. The inclined step portion 31 n,which abuts against and receives the edge portion 47 of the inclinedsurface 46 of the tubular filter 40, is formed in the filteraccommodation chamber 31 g. In addition, the opening 44, formed in thetubular filter 40, communicates with the flow path 31 j when theinclined surface edge portion 47 and the inclined step portion 31 n abutagainst each other so as to bring the two into coincidence with eachother. The flow path 31 j in the filter accommodation chamber 31 g andthe opening 44 in the filter 40 are automatically brought intocommunication with each other. Therefore, when the tubular filter 40 isinserted in the filter accommodation chamber 31 g the edge portion 47 ofthe inclined surface 46 of the tubular filter 40 abuts against (or fitinto) the inclined step portion 31 n of the filter accommodation chamber31 g.

[0074] This helps make the mounting job of the filter 40 and the lid 50even easier.

[0075] (c) Part of the inner peripheral surface of the filteraccommodation chamber 31 g and part of the outer peripheral surface ofthe tubular filter 40 are formed into a flat surface (31 m, 45). Inaddition, there is formed in the tubular filter 40 the opening 44 thatcommunicates with the flow path 31 j when the flat surface portion 45 ofthe tubular filter 40 and the flat surface portion 31 m of the filteraccommodation chamber 31 g are brought into coincidence with each other.When the tubular filter 40 is inserted into the filter accommodationchamber 31 g so as to bring the two flat surface portions 31 m and 45into coincidence with each other, it automatically causes the flow path31 j in the filter accommodation chamber 31 g to communicate with theopening 44 in the filter 40.

[0076] The mounting job for the filter 40 and the lid 50 will thereforebecome even easier.

[0077] While the invention has been described with reference topreferred embodiments thereof, it is to be understood that the inventionis not limited to the preferred embodiments or structures. Rather, theinvention is intended to cover various modifications within the spiritand scope of the invention.

[0078] The invention being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A water jet propeller including a water intakeport having a filter being disposed therein and being provided in a sidewall of a stator containing a rotatable impeller comprising: a tubularfilter accommodation chamber being formed in the side wall of thestator, said tubular filter accommodation chamber forming the waterintake port; a tubular filter being positioned within the filteraccommodation chamber; and an opening formed in a circular shape in thefilter accommodation chamber and being closed by a circular lid withscrew threads.
 2. The water jet propeller according to claim 1, whereina flow path is integrally formed with respect to a peripheral wall ofthe filter accommodation chamber, a bottom portion of the tubular filteris formed by an inclined surface that is inclined with respect to anaxial direction of the tubular filter, an inclined step portion isformed in the filter accommodation chamber so as to abut against andreceive an edge portion of the inclined surface of the tubular filter,and an opening, which communicates with the flow path when the inclinedsurface edge portion abut against the inclined step portion so that thetwo portions are brought into coincidence with each other, is formed inthe tubular filter.
 3. The water jet propeller according to claim 1,wherein a flow path is integrally formed with respect to a peripheralwall of the filter accommodation chamber, an inner peripheral surface ofthe filter accommodation chamber and an outer peripheral surface of thetubular filter are partially formed into a flat surface, and an opening,which communicates with the flow path when the flat surface portion ofthe tubular filter coincides with the flat surface portion of the filteraccommodation chamber, is formed in the tubular filter.
 4. The water jetpropeller according to claim 2, wherein said tubular filter iscylindrical in shape and includes the inclined surface formed integrallytherewith, said inclined surface forming a bottom of said tubularfilter.
 5. The water jet propeller according to claim 4, wherein saidinclined surface includes a plurality of apertures in communication withwater being disposed within said stator.
 6. The water jet propelleraccording to claim 3, wherein the opening in said tubular filter extendsfrom one end that is brought into communication with a flow path whensaid tubular filter is inserted into said filter accommodation chamberwith said flat surface being aligned relative to each other.
 7. Thewater jet propeller according to claim 6, wherein the flat surface onsaid tubular filter is offset by a predetermined angle relative to saidopening in said tubular filter.
 8. A water jet propeller including awater intake port having a filter being disposed therein and beingprovided in a side wall of a stator containing a rotatable impellercomprising: a tubular filter accommodation chamber being formed in theside wall of the stator, said tubular filter accommodation chamberforming the water intake port; a tubular filter being positioned withinthe filter accommodation chamber; and an opening formed in a circularshape in the filter accommodation chamber and being closed by a circularlid by press-fitting.
 9. The water jet propeller according to claim 8,wherein a flow path is integrally formed with respect to a peripheralwall of the filter accommodation chamber, a bottom portion of thetubular filter is formed by an inclined surface that is inclined withrespect to an axial direction of the tubular filter, an inclined stepportion is formed in the filter accommodation chamber so as to abutagainst and receive an edge portion of the inclined surface of thetubular filter, and an opening, which communicates with the flow pathwhen the inclined surface edge portion abut against the inclined stepportion so that the two portions are brought into coincidence with eachother, is formed in the tubular filter.
 10. The water jet propelleraccording to claim 8, wherein a flow path is integrally formed withrespect to a peripheral wall of the filter accommodation chamber, aninner peripheral surface of the filter accommodation chamber and anouter peripheral surface of the tubular filter are partially formed intoa flat surface, and an opening, which communicates with the flow pathwhen the flat surface portion of the tubular filter coincides with theflat surface portion of the filter accommodation chamber, is formed inthe tubular filter.
 11. The water jet propeller according to claim 9,wherein said tubular filter is cylindrical in shape and includes theinclined surface formed integrally therewith, said inclined surfaceforming a bottom of said tubular filter.
 12. The water jet propelleraccording to claim 11, wherein said inclined surface includes aplurality of apertures in communication with water being disposed withinsaid stator.
 13. The water jet propeller according to claim 10, whereinthe opening in said tubular filter extends from one end that is broughtinto communication with a flow path when said tubular filter is insertedinto said filter accommodation chamber with said flat surface beingaligned relative to each other.
 14. The water jet propeller according toclaim 13, wherein the flat surface on said tubular filter is offset by apredetermined angle relative to said opening in said tubular filter. 15.A cooling water flow path adapted for use in cooling an enginecomprising: a water intake port having a filter being disposed thereinand being provided in a side wall of a stator containing a rotatableimpeller: a tubular filter accommodation chamber being formed in theside wall of the stator, said tubular filter accommodation chamberforming the water intake port; a tubular filter being positioned withinthe filter accommodation chamber; and an opening formed in a circularshape in the filter accommodation chamber and being closed by a circularlid; wherein water supplied from said water intake port and through saidtubular filter is adapted for being supplied to an engine for coolingthe engine.
 16. The cooling water flow path adapted for use in coolingan engine according to claim 15, wherein a flow path is integrallyformed with respect to a peripheral wall of the filter accommodationchamber, a bottom portion of the tubular filter is formed by an inclinedsurface that is inclined with respect to an axial direction of thetubular filter, an inclined step portion is formed in the filteraccommodation chamber so as to abut against and receive an edge portionof the inclined surface of the tubular filter, and an opening, whichcommunicates with the flow path when the inclined surface edge portionabut against the inclined step portion so that the two portions arebrought into coincidence with each other, is formed in the tubularfilter.
 17. The cooling water flow path adapted for use in cooling anengine according to claim 15, wherein a flow path is integrally formedwith respect to a peripheral wall of the filter accommodation chamber,an inner peripheral surface of the filter accommodation chamber and anouter peripheral surface of the tubular filter are partially formed intoa flat surface, and an opening, which communicates with the flow pathwhen the flat surface portion of the tubular filter coincides with theflat surface portion of the filter accommodation chamber, is formed inthe tubular filter.
 18. The cooling water flow path adapted for use incooling an engine according to claim 16, wherein said tubular filter iscylindrical in shape and includes the inclined surface formed integrallytherewith, said inclined surface forming a bottom of said tubularfilter.
 19. The cooling water flow path adapted for use in cooling anengine according to claim 18, wherein said inclined surface includes aplurality of apertures in communication with water being disposed withinsaid stator.
 20. The cooling water flow path adapted for use in coolingan engine according to claim 17, wherein the opening in said tubularfilter extends from one end that is brought into communication with aflow path when said tubular filter is inserted into said filteraccommodation chamber with said flat surface being aligned relative toeach other.
 21. The cooling water flow path adapted for use in coolingan engine to claim 20, wherein the flat surface on said tubular filteris offset by a predetermined angle relative to said opening in saidtubular filter.